Turbine type hydraulic torque converter



STANLEY MAYNER INVENTOR ATTORNEY Dec. 30, 1952 s MAYNER TURBINE TYPE HYDRAULIC TORQUE CONVERTER Filed Nov. 29, 1947 Patented Dec. 30, 1952 TURBINE TYPE HYDRAULIC TORQUE CONVERTER Stanley Mayner, Cleveland Heights, Ohio, assignor of two-fifths to Thomas S. Mayner, Russel Township, Ohio Application November 29, 1947, Serial No. 788,909

12 Claims.

' This invention relates to a power transmitting apparatus and, more particularly, to a hydraulic powertransmitting apparatus such as a turbine type torque converter adapted to be combined with gearing.

The torque converter of this invention advantageously provides for continuing high initial torques over a long torque ratio range, and for a continuous flow of uniform power. The torque converter is also adapted to provide for power output in either direction of the output shaft, in the same advantageous manner over substantially the same torque range. Generally all torque converters have included in their fluid circuits a reaction member as an essential element. The converter of this invention omits such a member by, advantageously, a differential operation of its turbine members and an exterior means for holding one of. the turbines from reverse rotation.

to acton afirst driven fluid reacting turbine.

member applying its force thereto then to be guided thereby to a second impeller where the head isincreased. The increased head then acts.

onja'second turbine member whose rotation is translated into high torque ratios. increase is eifected by, advantageously, two fluid energizing members or impellers mounted for rotation in a parallel manner so that they act on the fluid in series, i. e; the first impeller creates an initial driving head which head with substantially no loss of energy is directed by the first turbine member to the second energizing member where it is increased. The head of the fluid thus built up acts on the second turbine member-whose rotation is initially translated into torque output. v u

In the fluid circuit there are positioned, in an operative relation, at least one fluid reversing turbine member at the outlet of each energizingmemben or fluid impeller. Each fluid reversing turbine member is adapted to rotate inde- The turbines utilized in the-converter are advantageously of The head pendently of the other, being subject only to the fluid heads of the fluid energizing members. Their rotation is differentially combined through gearing to drive an output shaft. The differential operation of the turbines enables one toinitial- 1y rotate while the exterior holding means .prevents the other turbine from reverse rotation and also causing it to act as a reacting member until it also can assume the load. The fluid reversing turbine members comprise an annular plurality of buckets or fluid receiving and reversing members positioned in angular planes substantially parallel to the common axis of rotation and desirably having their inlets and outlets facing inwardly into the interior of the converter. The turbine members are the subject of an application Serial No. 454,639 filed August 13, 1942 that has issued as Patent No. 2,432,115. By being reversing and when held stationary, the turbines are adapted to take the full fluid pressure and redirect or guide the fluid to a subsequent member, such as an impeller. Thus, when the first turbine member is held from substantial rotation by being loaded by the second turbine through the differential gearing the energizing fluid loses very little head while flowing through it to the second energizing mem her where the head is increased prior to its acting on the second turbine.

After the initial torque requirements are satisfied and the first turbine is released the second turbine and impeller become coupled; the first turbine then assumes the job of overcoming the remaining torque. Eventually the two turbines will rotate in union to form a completed coupling.

As mentioned hereinbefore the turbine members, advantageously, are differentially interconnected through gearing. The gearing can, of course, be utilized to further modify the torque output of the turbine or driven members.

There is provided through the aforesaid. arrangement of members a continuous elasticity in meeting desired torque ratios. The arrangement also enables the use of whatever energy there remains in the fluid upon leaving the second turbine to build up the initial head and thus ease the load on the primary energizing element.

The torque converter of this invention will be more specifically described in the following specification and accompanying drawing, where:

Figure 1 represents a cross section of the torque converter;

Figures 2 and 3 are partial sectional representations of the and fluid reversing turbines utilized;

Fgure 4 is a schematic diagram of the apparatus of Figure l.

The torque converter of Figure 1 comprises two fluid energizing members it and ii arranged to rotate with the power input shaft I2. The section of the shaft within the converter can be solid or it can be eliminated if so desired. The elimination of the shaft from the interior of the converter will provide for a substantially more uniform. and unimpeded flow of the Working fluid from the second turbine element of the converter to the energizing member It provided all entry points are proper 1y curved and are clean and sharp. In view of the elimination of shafting from the interior of the converter the energizing member H is, then, advantageously mounted on a tubular shaft or sleeve I5 which forms a part of the guiding wall of the energizing member Iii. The turbines I5 and it rotate about the tubular shaft I4 on sleeve-type bearings i3, I3A respectively.

There is operatively positioned a turbine element ordriven member 15 adjacentth'e' outlets of the energizing. member I5. The driven member or turbine I15" comprises an annular series of fluid receiving and reversing buckets I3 superposed in a tangential manner to form adiscontinuou's, generally circular periphery. The structure and angu'l-arity of position of the fluid receiving and reversing turbine members i5; I8 is more" specifically shown in Figures 2 and 3'. As there shown the buckets or fluid passages I5, I8A are substantially fully reversing. They are positioned in a generally superposed manner to form the circumference of the turbine; ing plane of each bucket'is substantially parallel to the axis: of rotation of the turbine and the inlets and-"outlets of the buckets are in lines sub stantially parallel to the turbine axis.

advantageously, such a. turbine member construction will utilize to the fullest degree the fluid forces; acting upon it,. "io'r the fluid is at the farthest radius possible and acting in the direction of rotation. The" fluidiis thenredirected'an'd the remaining forces, without appreciable further' loss, are guided to a succeeding member. For example, with the unit under a load which is'tobe overcome the fiuidienergizing members It and II force the fluid through the turbines I5 and I6. The rotation of the turbines is then translated. intoito'rque" output through differential gearing. Turbine I6 assumes the initialresponsibilityror overcoming the load and because of being. difierentiallyfg'eared to turbine I5 it starts substantially immediately to rotate while turbine I5 is held. from rotation. In a continuous-and.

substantially.undisturbed manner the fluid is forced through the first turbine, the fluid energy being utilized thereby to the fullest eXt-ent'then it is redirected orguidediwith onlysuch anren'e'rgy loss as that absorbed by the turbine It andifriction losses to'theim peller II where the incominghead is increased to 'b'e directed into the second turbine I5. As-the' load is overcome the turbine It increases in speed and. the first turbine It startsto rotate W'h e'r i the speed'df turbine I6 approaches that of the impeller I I the two members assume ac'oupl'ing'sta't'u s. When turbine- I 5 and impeller I"! become coupled the first turbine then assumes the load, and upon overcomin it the turbine I5 andimpeller I will also assume a coupling status placing the entire unit into a coupling as well as into a direct drive.

The fluid reversing turbine I is "desirably, integrated into a torque converter housing I9 which The po sitionis suitably sealed about the power input shaft I2. The housing I9 also forms the fluid flow path and encompasses the second fluid energizing member II, and the second turbine element It which is constructed similarly to the turbine I5. The turbine I5 is also operatively positioned adjacent the fluid outlets of the second energizing member I I. The housing, additionally; encompasses a differential gearing compartment 2I in which are positioned a suitable number of planetary gear 7 l5 into the second energizing member II; and

the guiding path 26 is adapted to direct the flow of the working fluid back into the first energizing member ID.

Advantageously the impellers I5 and II are of the curved blade type. Whatever head or energy. then, that is left in the fluid when itleaves the second turbine I6 assists the first impeller in that it tends to increase the initial head. Furthermore the working fluid is better directed into the turbine buckets which are positioned at an angle in the direction of their rotation.

In the arrangement shown the secondary turbine I5 is adapted to rotate independently of the first turbine I5. bearings about the sleeve IA and about the stub section of the output shaft 30. The housing I9, thus, not only incorporates the turbine I5 but also, advantageously, encloses all of the other working parts of the converter and the differential gearing.

The energies of both turbines of the converter are transmitted to the output shaft 35 through a sun gear 3| mounted on the shaft. About the output shaft and within the sleeve 24 there are rotatably positioned two-sleeve members "32,

33. The sleeve, members have mounted on them sun gears 35, 36 at one of their ends and splined sections 31, 38 at the other of their ends. Sun gear 3l and the sleeve mounted sun gears 35, mesh with a corresponding number of comple- .mentary' planet gears which are hereafter identifled as beingipart of the planetarygear cluster 22. The gear cluster22 is composed of gears 40, 4I and 42 which mesh with the shaft gear 3I,"the' sleeve gear '35 andsleeve gear 36, respectively. The gear cluster is mounted-on a stub shaft 43, which is suitably rotatably secured to the second turbine member I3. The gear cluster 22 is then adapted to rotate with the turbine I6, and the gears of the cluster are adapted to react against the sleeve'm'o-unted gears 35, 36 when held to;

cause a rotation oi -the output shaft 30.

Advantageously the sleeve mounted pinion or sun gears 35 and 36 are adapted to be selectively.

The turbine revolves on suitable.

Ajsleeve 45 is desirably splined on.

member 41 there is a yoke 56 which rides in an annular groove on the sleeve 45. There is further provided at one end of the sleeve 45 an external splined section 53 which is adapted to engage in meshing relation an internal spline 54 in the stationary member 55.

Within the stationary member 55 there is provided a one-direction brake 60. The brake 60 is also mounted about and secured to the sleeve 24 in order to prevent the turbine I5 and the housing I9 from rotation in an opposite direction. The brake serves to tie the sleeve 24 through splines 46 through the movement of splined sleeve 45 so that the splined section 43 engages the splined section 38 on the sleeve 32, the sleeve 38 on which is mounted the gear 35 is thus tied to the housing I9 to thereby provide reaction for cluster gear 4| enabling it to drive the sun gear in a forward direction. Otherwise, if the sleeve 24 were not held by the one-way brake 60 then the housing I9, that is, the turbine |5 would rotate in a reverse direction due to the reaction of the gear 4| which is driven by the initially responsive turbine I5. The brake 60 is thus adapted to hold sleeve 24 only until such time when turbine I5 starts to assume the load, then the sleeve 24 will rotate to drive gear 35.

For a forward motion of the output shaft 33 the yoke carrying sleeve 45 is moved into engagement with the rear spline 38 of the sleeve 32. Sleeve 32 carries the sun gear 35 which meshes with gear 4| of the gear cluster 22. Since the sleeve 24 is attached to the housing 9 and therethrough to the turbine I5 the turbine is kept from substantial initial rotation by the reactance of gear 35 on gear 4| because of a difference in gear diameters. The gear 4| as a result rotates about the sun gear 35 to drive the shaft 30 through its sun gear 3|.

As the second turbine I5 increases in speed of rotation its reaction or loading on the sun gear 35 decreases thereby enabling an ever increasing rotation of the sleeve 24 and of the gear 35 thus, the turbine l5 assumes more and more of the load. The second turbine upon a substantial reduction of the torque requirements will approach the speed of the impeller II and thus merge into a coupling status. During this interval. the first turbine I5 continues to assume more load until it takes over the entire load. The turbine I5, if uninterrupted because of load changes, will also approach a coupling stage and the differential placed upon the sun gear 3| because of the different speeds of rotation of the turbines disappears. When the aforesaid situation arises a substantially direct drive occurs.

, Should there occur a further torque requirement turbine I5 will promptly undertake its solution if it can alone, otherwise, the torque would have to be redistributed between the two turbine members. Their rotation is immediately differentially'translated to the output shaft. Further a very large torque range can be provided for by varying the size of the sun gear 35 and of its complementary planet gear 4|. Advantageously, the planet gear 4| as shown in the drawing is greater in diameter than the sungear 35 driven by the first turbine I5 so that the second turbine can primarily meet the torque requirements.

I Reversal of rotation of the output shaft is also provided. The change in direction of rotationiseffected through gearing. The splined sleeve 4.5 ismoved to effect the meshing of the external guides the fluid to the next impeller.

splines 53 which mesh with the internal splines- 54 of the stationary member 55. Simultaneous-- ly the splines 46 of the sleeve 45 will mesh with the splines 31 of sleeve 33. The splinedsleeve 45 thus will keep the sleeve 33 from rotation while sleeve 32 is released to move freely. Since sleeve 33 is held the planet gear 42 will rotate or turn about the sleeve mounted; sun gear 36.. Further, because of the gear size differences the motion of the planetary system'will cause. a; change in'the direction of the rotationofthe output shaft 30. i' i 31?! The operation of the torque converter of this invention is also schematically shown. There, is shown in Figure 4 the fluid flow path and the" advantageous positioning of the various elements of the converter. A power input shaft I2 is adapted to drive two separate energizing mem bers I0 and IL Fluid leaving the energizing member I0 traverses the fluid receiving and re-' versing turbine I5 which is kept from rotation by the load or reaction on the unit. The turbine I5 because of its construction is of course urged to move forwardly and at the same time The fluid while activating the first turbine flowson with its retained energy to the second impeller II. The energy head of the fluid is further increased by the second energizing member II, which may be said to be an energy booster, to act on the second turbine I6. With the increased: high" head acting on the turbine I6 which is; advantageously geared high initial torque ratios are produced. The working fluid is further ad' vantageously redirected by the structure of the second turbine I6 and the open wall construction of the converter into the first energizing member ID to boost the initial head output of the working fluid by whatever energy head may still be in the fluid. i

The second turbine I5 as shown has attachedto it a planetary gear system containing gears 40, 4|, 42. These gears rotate about sleeve mounted sun gears 3|, 35, 35. Gear 3| drives the output shaft while gears 35 and 36 act-as reaction gears for forward and reverse motion respectively. Gear 35 is adapted to be: held by the splined sleeve 45 when the sleeve splines 38 mesh in the splines 46 since similarly, gear 36 is held by splined member 38 which is held by the splined sleeve member 45. Splined sleeve '45 is, of course, kept from rotation whenit is. in mesh with splines 54 of the stationary mem ber 55. I 53 When the rotative differential betweenv the planetary gears 4| and the sun gear 35 approaches a certain value the second impeller II and turbine IE will assume a coupling status, and they will remain so for the interval that the first turbine takes over. When the load or reaction of the gear 4| on sun gear 35 is reduced so that the gear 35 assumes the driving load the brake 6|] releases the sleeve 45 and the first turbine as sumes the burden. Without further changes in load the first turbine and impeller also become coupled. When this condition comes about both turbines will rotate at substantially the same speeds, the first however primarily bearing the load, the gearing becoming, locked in a straight forward transmission of the power of the primary mover. Such a situation will create a coupling of the torque converter.

Sometimes there will occur a greater rotation of the output shaft over the input shaft for erg-Q m e. While l 1 On I Q-fihe .cnnverter is go'ing down. hill. .It may :be desirable .llnder .such a'condition .to utilize the actionof the converter to slow down the vehicle to about the decreased rotation'of the input power shaft. The turbine. members 16 and. i are-adapted at ,such

to act as .pumps for driving, the working. .fluidra gainst the energizing members. which are positioned :on the: input shaft; Actually, the secondary-turbine I 6 will rotate, being driven by gears-35i fl while the first turbine I5 will act as apfiui'd redirector, since advantageously the hous ing. l9 becomes locked to the input ShaftqtO pre- Ventits reverserotation. Upon a reversal of -flow the; housing [9 containing the turbine is willtend toifioat. unless it is held to the inputshaft i2.

Thus. :heldrit becomes a reacting member for thereversed :fluid which is redirected to the, first impeller :l fl. .The housingis held by somesuitableadevice such. as. a onea'way clutch-64 posi- .tiohedain'front. of thehousing 19 about the input The housing, [9 can beheld to the shaft 12. inputsshaft l2 since-.braket'il become ineifective .an'd clutch Ed -becomes. effective. The turbine I 5 in reversingthe flowof the fluid drivesit against impellerl l thence through the lockedturbin lficagainst the impeller .10 to-thus-e'ffectively retafd a vehicle employing the converter. "Ihus through-such.zcounteraction ,of the fluid on the energizing membersrt-he convertercan be utilized as'iabrakihgdeyice to slow down themotion-oi a:

vehicle.

Advantageously turbine. i6 is geared higher becauseaof being highly. geared. Turbine [5,; as

arr'esultywill;fail.tobecome coupled with its. im-

'peller:untiltit;overcomesithe difierence. in thegear ratiosrbetween itself: and;turbine.. it. The possibility,,then,.sexists thatracompleted coupling may onlyxrarelytbeihad; since. there. is. always. some:

inertia .totbes; overcome. Although: the drawing shows the: turbi'nesatobe nearly: equal in :diameter solthat'. substantially equal torques wouldactuate thempthe: relative diameters of turbines l5: and I6 can advantageously be varied, or their size to equalizeithe. torques. in .the event. of the turbines beingzdifierently. geared. .Thus, the. diameter of turbine l5 canbe increasedto the extent of providingLtorquer compensation: forthe difference in. thee-turbinev gear ratios. 5 Since torque increases as the'fdiameter to the fi f th power it would require butia-sma-ll extension ofthe "diameter of. a turbine tocompensate for even a substantial gear ratio difference. "The turbine 15,- then,--can have a slightly--greater -'diameter than turbine i 6 so;

that-their torquesare substantially equal-even though being difierentially geared; and the gears being of different diameters. By beingequalized in' the aforesaid manner theconver-terwvill, upon an equalization of torque-on the turbines; become a full coupling.

In the drawing turbine It is shown as bein more highly geared than turbine-15. The arrangement-can be reversed, if desired, and the result would be substantially thesame. Further additional stages in series-can'be added to the Also When-it becomes:

8. o e i r t e s me an ersno ihg eh thedisclosure is limited to one embodiment.

I claim l. A fluid torque converter comprising a pair of fluid energizing members, a fluid driven turbine member positioned-adjacent. the fluid outlets of each of said fluid energizing membe and between th said tur es be n .o dif ere t sizes and being adapted to be individually driven,

sears sociated with sai u b nes p r ifie entially interconnecting, them and for transmitting their torques, said gears. being of different diameters so that one of said turbinesis adapt d.

to rotate a-ta greater rate than theother of said turbines, andsaid lesserrate turbine being larger an extent to substantially compensate; for torque differences between said turbinescaused. by the different gear-diameters.

.2; In a fluid torque con verter, at least tWO- individually driven turbine: members, means for differentially interconnecting said turbine ,members comprising, a planetary gear set hayingat least two gears rotatably fixed to one oipsaid turbine members, a sungear in meshing relation with each. of said planetary gears, an output shaft, one of said sun gears beingmountedpn said output shaft, and said other of said sun gears being ,operatively associated with- ,the other of said turbine members.

.3. .In a. fluid torque converter,,at least two individually driven turbine members, means for differentially interconnecting said turbinemembers comprising, .a planetary earset'fixedto'one of said turbinemembers, anoutputshaft having a sungear: in meshing relation withioneof the. gears of said planetary gearset, a irotatnbl mounted sleeve member. about said Output :sh r fi having. a sun gear, said sun .gearbeingzin. meshing.

relation with another of .thegearsof saidpla ne tary gearset,;and means for. drivinglyconnect-ing the. other or; said turbine. members with said. SEC. ondsun gear of" said rotatably' .sleeve mounted member.

.4. In a ifluid. torque converter, at 1 least. two injdividually driven. turbine: members, .means .for: drivingly interconnecting. said turbine. members,

an. output shaft, -.-a planetary gearset havingra plurality of: gears fixed to one of .said: turbine members; a sun. gear onsaid. output shaft-being irr meshing relationwithone: set of gears of said gearset, a rotatably mounte'dsleeve about said.

output shaft having a sungear, said sleeve mounted sun. gearbeing inmeshing relation with another set of planet-gearsof said gearset, means.

for drivingly-connectingthe othertu-rbinewith said sleeve mounted sungear, means for holding said sleeve from opposite rotation, a second rotatably mounted sleeve havinga sun gear, said sun gear on -said second sleeve member being in meshing relation with; a nother'ofsai'd planetary gears of said set, and-means 4 for; holding said' seoQ ld' sleeve'whereby thedirection of theoutputshaft.

is reversed.

'5. In -a fluid torque-converter, at least UWOiIldividually driven turbine members, means for drivingly interconnecting said turbine members.

a planetary gearset fixed to one of said turbine members, an outputsha-it, asun gear-onsaidoutput shafti-n meshing-relation with said gearset, a sleeverotatably mounted about said-output shaft having a sun gear, said sleeve mountedasun gear being in meshingrela-tionwith gears-of said planetary gear-set, meansfor drivinglyconnecting; the other ofsaid turbines withsaid s-1eeve,-means. associated with said" sleeve for prevent-ingth'e rm" tation of said latter turbine in a reverse direction, said sleeve mounted sun gear and its complement gear of said planetary set being of different diameters to thereby provide reaction for and permit prior rotation of the turbine with the gearset, said turbine rotation preventing means becoming inoperative upon a predetermined torque on said first turbine permitting a jointly differentially adjustable actuation of said output shaft, and a second rotatably mounted sleeve member having a sun gear, said sun gear being in meshing relation with said planetary gearset, and means for holding said second sleeve from rotation to thereby reverse the direction of rotation of said output shaft.

6. In a power transmitting apparatus, at least two fluid energizing members mounted on the same shaft and in the same fluid circuit, said energizing members having curved blades, independently rotating turbine members operatively positioned adjacent the fluid outlet portions of said energizing members and being actuated by the energized fluid, the fluid being primarily and additionally energized by said energizing members, said turbine members having a plurality of circumferentially positioned inwardly facing fluid receiving and reversing buckets positioned at acute fluid receiving angles, the inlets and outlets of said'buckets being in lines substantially parallel to the axis of rotation of the turbines, and a curved path defined by the walls of the turbine members and of the energizing members for redirecting fluid into the curved blades of the energizing members.

7. A torque converter comprising, an input shaft having two spaced impellers, fluid receiving and reversing turbines positioned adjacent the fluid outlets of each of said impellers, said turbines being adapted to be individually driven relative to each other in the same direction, a planetary gear system having a rotatable planet gearset associated with one of said turbines and rotating therewith, a sun gear associated with the other of said turbines, a sun gear mounted on an output shaft, both said sun gears being in meshing relation with said planet gearset, and said gearset being rotated by the relative rotation of said turbines and being adapted to drive said output shaft mounted sun gear.

8. A power transmitting apparatus comprising,

a fluid circuit, at least two fluid energizing members acting in series in said fluid circuit, said members energizing fluid in a radially outward direction to their axes of rotation, and individually driven turbine members positioned in said fluid circuit adjacent said fluid energizing members, each of said turbine members comprising a plurality of fluid direction changing passages having radially outwardly positioned inlets and radially inwardly positioned outlets with respect to the axes of said turbine members.

9. A power transmitting apparatus comprising, a fluid circuit, at least two fluid energizing members acting in series in said fluid circuit, said members energizing fluid in a radially outward direction to their axes of rotation, individual turbine members positioned in said fluid circuit adjacent said fluid energizing members, each of said turbine members comprising a plurality of fluid direction changing passages having radially outwardly positioned inlets and radially inwardly positioned outlets with respect to the axes of said turbine members, and means for guiding the fluid leaving said turbine members to said fluid energizing members.

10. In a power transmitting apparatus having a fluid circuit, at least two independently rotating rotors arranged in a series relation in said fluid circuit, and each of said rotors comprising a plurality of passages positioned in planes generally parallel to the axis of said rotors, said passages having inlets positioned in a radially outward direction and outlets positioned in a radially inward direction with respect to their axes of rotation.

11. A fluid power transmitting apparatus comprising a fluid circuit, at least two fluid energizing members acting in series and positioned in said fluid circuit, individually rotating turbine members rotating in the same direction when driven by the energized fluid, each of said turbine members being axially spaced and comprising a plurality of passages positioned in planes generally parallel to their axes of rotation, said passages having inlets positioned in a radially outward direction and outlets positioned in a radially inward direction with respect to their axes of rotation, and a portion of one of said turbine members and of one of said energizing members forming a fluid direction changing means between said turbine members.

12. A fluid power transmitting apparatus comprising a fluid circuit, at least two fluid energizing members acting in series and positioned in said fluid circuit, individually rotating turbine members rotating in the same direction when driven by the energizing fluid, each of said turbine members being axially spaced and comprising an annular plurality of passages positioned in planes generally parallel to the axes of rotation of said turbine members, said passages having inlets positioned in a radially outward direction and outlets positioned in a radially inward direction with respect to their axes of rotation, a portion of one of said turbine members and of one of said energizing members acting as a fluid direction changing means between said turbine members, and means for axially redirecting fluid from one of said turbine members through the core of said power transmitting apparatus to one of said fluid energizing members.

STANLEY MAYNER.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,855,967 J andasek Apr. 26, 1932 1,993,741 Jandasek Mar. 12, 1935 2,055,895 Fawcett Sept. 29, 1936 2,416,948 Pavlecka Mar. 4, 1947 FOREIGN PATENTS Number Country Date 442,363 Great Britain Feb. 3, 1936 

